Added XPathExpressionFactoryBean.

xml/src/main/java/org/springframework/xml/xpath/Jaxp13XPathExpressionFactory.java

@@ -17,18 +17,16 @@
 package org.springframework.xml.xpath;
 
 import java.util.Map;
-
 import javax.xml.namespace.QName;
 import javax.xml.xpath.XPath;
 import javax.xml.xpath.XPathConstants;
 import javax.xml.xpath.XPathExpressionException;
 import javax.xml.xpath.XPathFactory;
 
+import org.springframework.xml.namespace.SimpleNamespaceContext;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 
-import org.springframework.xml.namespace.SimpleNamespaceContext;
-
 /**
  * JAXP 1.3-specific factory creating <code>XPathExpression</code>s.
  *
@@ -85,9 +83,7 @@ abstract class Jaxp13XPathExpressionFactory {
         }
     }
 
-    /**
-     * JAXP 1.3 implementation of the <code>XPathExpression</code> interface.
-     */
+    /** JAXP 1.3 implementation of the <code>XPathExpression</code> interface. */
     private static class Jaxp13XPathExpression implements XPathExpression {
 
         javax.xml.xpath.XPathExpression xpathExpression;
@@ -107,7 +103,10 @@ abstract class Jaxp13XPathExpressionFactory {
 
         private Object evaluate(Node node, QName returnType) {
             try {
-                return xpathExpression.evaluate(node, returnType);
+                // XPathExpression is not thread-safe
+                synchronized (xpathExpression) {
+                    return xpathExpression.evaluate(node, returnType);
+                }
             }
             catch (XPathExpressionException ex) {
                 throw new XPathException("Could not evaluate XPath expression:" + ex.getMessage(), ex);

xml/src/main/java/org/springframework/xml/xpath/XPathExpressionFactoryBean.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2007 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.xml.xpath;
+
+import java.util.Properties;
+
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.util.Assert;
+
+/**
+ * Spring {@link FactoryBean} for {@link XPathExpression} object. Facilitates injection of XPath expressions into
+ * endpoint beans.
+ * <p/>
+ * Uses {@link XPathExpressionFactory} underneath, so support is provided for JAXP 1.3, Jaxen, and Xalan XPaths.
+ *
+ * @author Arjen Poutsma
+ * @see #setExpression(String)
+ */
+public class XPathExpressionFactoryBean implements FactoryBean, InitializingBean {
+
+    private Properties namespaces;
+
+    private String expressionString;
+
+    private XPathExpression expression;
+
+    /** Sets the XPath expression. Setting this property is required. */
+    public void setExpression(String expression) {
+        expressionString = expression;
+    }
+
+    /** Sets the namespaces for the expressions. The given properties binds string prefixes to string namespaces. */
+    public void setNamespaces(Properties namespaces) {
+        this.namespaces = namespaces;
+    }
+
+    public void afterPropertiesSet() throws IllegalStateException, XPathParseException {
+        Assert.notNull(expressionString, "expression is required");
+        if (namespaces == null || namespaces.isEmpty()) {
+            expression = XPathExpressionFactory.createXPathExpression(expressionString);
+        }
+        else {
+            expression = XPathExpressionFactory.createXPathExpression(expressionString, namespaces);
+        }
+    }
+
+    public Object getObject() throws Exception {
+        return expression;
+    }
+
+    public Class getObjectType() {
+        return XPathExpression.class;
+    }
+
+    public boolean isSingleton() {
+        return true;
+    }
+}